String dataOfBirth = "1991-10-21";<span style="white-space:pre">	</span>//出生日期

try {
            //此處是獲得的年齡
          int  age = getAge(parse(dataOfBirth));           //由出生日期獲得年齡***
        } catch (Exception e) {
            e.printStackTrace();
        }

//出生日期字串轉化成Date物件
    public  Date parse(String strDate) throws ParseException {
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
        return sdf.parse(strDate);
    }

    //由出生日期獲得年齡
    public  int getAge(Date birthDay) throws Exception {
        Calendar cal = Calendar.getInstance();

        if (cal.before(birthDay)) {
            throw new IllegalArgumentException(
                    "The birthDay is before Now.It's unbelievable!");
        }
        int yearNow = cal.get(Calendar.YEAR);
        int monthNow = cal.get(Calendar.MONTH);
        int dayOfMonthNow = cal.get(Calendar.DAY_OF_MONTH);
        cal.setTime(birthDay);

        int yearBirth = cal.get(Calendar.YEAR);
        int monthBirth = cal.get(Calendar.MONTH);
        int dayOfMonthBirth = cal.get(Calendar.DAY_OF_MONTH);

        int age = yearNow - yearBirth;

        if (monthNow <= monthBirth) {
            if (monthNow == monthBirth) {
                if (dayOfMonthNow < dayOfMonthBirth) age--;
            }else{
                age--;
            }
        }
        return age;
    }